Abstract 346P
Background
Relapse is the major treatment failure of allogeneic hematopoietic stem cell transplantation (HSCT) in patients with hematologic malignancies. Tumor-infiltrating T cells play an important role in disease progression and recurrence.
Methods
We used flow cytometry to classify T cells into five subtypes using CD45RA, CD95, and CCR7. We defined early relapse (ER) as relapse within 6 months of allogeneic HSCT. High-throughput single-cell RNAseq assays from BM lymphocytes isolated by density gradients were performed to determine the expression and cell composition of previously irradiated markers.
Results
With this approach, marrow-infiltrating T cells were analyzed in 40 patients (10 patients with early relapse) with a median age of 57 years (ranged from 30 to 71). Marrow-infiltrating CD3+T cell counts were lower in patients with allogeneic HSCT compared to normal subjects (CD3+T cells: 13.89% in HSCT patient and 9.116% in ER patients vs. 34.19% in normal subjects, p< 0.0001). In addition, CD3+CD8+T cells were higher in CR than ER patients (CD3+CD8+T cells: 50.39% in CR vs. 30.41% in ER patients, p< 0.0033). Of CD3+T cells, the proportion and expression level of TIM-3 was higher ER patients than in CR patients (56.33% in ER patients vs 39.20% in CR patients, p= 0.0185/MFI; 1873 in ER patients vs. 826.7 in CR patients, p= 0.0331). Of CD8+ EMRA T cell, the expression of TIM-3 was higher in ER patients than in CR patients (MFI; 1441 in HSCT patients vs 421.7 in normal, p=0.1038). Otherwise, of CD3+CD4-CD8-, The percentage of TIM3 was higher in ER patients than CR patients (80.33 % in ER patients vs 62.49% in CR patients, p= 0.0333). Single cell RNA sequencing showed a higher proportion of HCS (Hematopoietic Stem Cell)-like cells in relapsed patients (+10.14%, P=0.368) and a lower proportion of CD8+ T cells (-13.40%, p=0.068). The HSC-like cells in relapsed patients exhibited higher expression of TIM3 ligand than in CR patients.
Conclusions
Among the IRs, TIM3 had the highest expression of all cell groups (CD4 T cells, CD8 T cells and Treg) compared with other IRs at the early stage of allogeneic HSCT.
Clinical trial identification
This study is Not clinical trial.
Editorial acknowledgement
I want to present this study as poster.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
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